Luas karton = 1 m x 1 m = 1 m2 = 10.000 cm2
Luas kerucut = πr (r + √r2 + t2)
L = 30π (30 + √302 + 402)
L = 30π (30 + √900 + 1.600)
L = 30π (30 + √2.500)
L = 30π (30 + 50)
L = 30π (80)
L = 2.400 π cm2
L = 7.536 cm2
Jadi, Lisa bisa membuat jaring-jaring luas kerucut